Process of making sound-record tablets.



J. SANDERS. PROCESS OF MAKING SOUND RECORD TABLETS.

APPLICATION FILED MAB.. 30, 1905.

Patented May 3, 1910.

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UNrrED srarns PATENT clarion,

`JOSEPH SANDERS, F WASHINGTON, DISTRICT 0F COLUMBIA.

PROCESS 0F' MAKING SOUND-RECORD TABLETS.

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Specification of Letters Patent.

Original applicatio'n :tiled .April-0, 1904, Serial No. 204,024. Divided and this applieatlonlod larch,

To all who/mit may concern:

applicable for use in phonographs and graphophones.

The gramophone tablet which is used commercially, consists of a tfiat disk of hard rubber -or of an imitation of yhard rubber, having a sound record impressed on one or both surfaces in l'the-shape of a spiral Igroove of even depth, lthe groove 'itself being vlaterally undulating, and 'these lateral Aundula tions or sinuosities correspond to the recorded -sounld waves, which are reproduced from the tablet by causing the sinuosities to `react lupon a 'style land diaphragm, as is well Aknown to those skilled in 'the art.

vIn a phonograph or grapho hone record the groove -is not of uniform ldepth, but of varying depth, and the variations of depth in that-case correspond tothe recorded sound waves, which are then reproduced from the tablet by causing these vertical u-ndulations to react 'upon a style and Idiaphragm inthe manner well known to those skilled in the art.

The material of :the flat gramophone rec ord tablets is now almost luniversally a composition of 'matter =in which shellac is combined wit-h infusorial earth'or with 'barytm or yother like substances. The shellac serves as a binder for fthe powdery body of baryt-a or inusoria-l earth, und the mixture forms a mass, which, like hard rubber, is softened by heat, but is very hard when cold. 'The sound record is impressed upon such ltablets b y a metallic matrix on which the undulations correspond-ing ,to sou-nd lwaves appear in raiised lines. A lumjp lor mass 4ot lthe record maiteria'l, Which is thermoplastic, is heated until itis quite soft or -in a -doughy Serial No. 252,840.

condition, and then is placed u on the matrix and is pressed out into a isk, in .intimate contact with lthe matrix, by the -application of considerable force and 'this tablet of record material is kep't -in contact with the matrix until cool and hard. l-n order to serve its purpose the record Imaterial must, -when cold, be so hard, that -it will 'then not receive an impression from a matrix, will not elastically yield 'to and ywill not perceptibly wear under the action -o -a gramophone reproducing style; onl-y-'to'such materials do I apply 'the term Fgramophone record material. In this process it ,-is necessary that a considerable thickness or 'mass of the tablet material be used in order that the body of it form a yielding cushion for the impressed surface at lthe time when :the pressure is exerted ulpon it by the matrix. The impression obtained, rthat is to say, the spiral groove, is, under a'll corcumsta-nces, very shallow, rarely exceeding a depth of 1/300 of an inch, so that Iit would seem to be sulicient `to heat and soften the .tablet only yat its upper surface land leave the remamder quite hard. Experience, however,

has shown that such practice will not yield a good impression and that it is 'necessary that the record materia-l be yielding to aconsiderable depth and preferably throughout its whole mass in order that good impressions rom the matrix be obtained. This is one of the reasons why 4the record tablets are made of considerable thickness. Another reason for this practice is 'that the resinous tablet is rather' brittle, so that when dropped upon a hard table or upon a iha'rd -ioor it will crack and break if made as thin as -it might otherwise be made. The material employed, however, 'particularly the shelling,

Patented May Y3, 191.0.y

is qulte expensive, -and Eor this reason strength is frequent-ly sacri-ficedtofcheapness.

It is the object of -my .invention to minimum of resinous or similar record -material, but which nevertheless yields under the pressure of the matrix to a considerable depth, and which is also very much-stronger than the record tablets made taltogether -of the resinous compounds usually-employed.

In the accompanying drawing 1 s' ow a r0- duce a record tablet that contains on y 'ailthe record material.

cross section of a record tablet made in accordance with my invention.

In this drawing l represents a disk of card board, or other stiff, tough, fibrous material. This is made of the size usuallyV given to gramophone tablets; it has a hole 2 at the center for mountin on aturn-table when sound reproduction 1s desired. This disk is coated with a thin layer 3 of the resinous record material, adapted to receive, when heated, the impression of a sound record matrix; such impression is indicated at 4Q Since it is desirable to use no more of this material than is necessary, I preferably apply to the card board or other fibrous base, first a sizing 5 of rosin which will sink int-o the surface o'f the card board for a distance or may permeate the card board throughout, or any other kind of ,sizing that softens underheat, that is, it is thermoplastic, that well adheres to or sinks to a certain distance into the card board and to-which the superimposed layerof record material also well adheres, may be used. This sizing, by closi ing the pores of the surface of the card board, prevents the absorption by the body of the card board of the superimposed layer of record material, and when the sizing permeatesthe card board it acts as a binder for the'fibers, causing the tablet to retain its shape after pressing andmaking it more solid and compact, for, without the binding action of the sizing the card board fibers would tend' to return to their original shape when the pressure is relieved.

When rosin, which I refer as a sizing, is employed, I dissolve it 1n benzol, alcohol or other like solvent, and either dip the tablet into the solution and then Withdraw it and allow the solvent to evaporate, or this sizing can be applied by a brush.

Upon the sized paste board or other fibrous diskthe record material may be applied in any desired manner, but in order that the record material form a uniform and at the same time thin layer, I have found that it is best that it be applied in a fluid state. For this urpose the record material may be dissolved in a suitable solvent and the sized disk .dipped into that mass or painted with the same, so that after theI evaporation of the solvent there remains upon thesurface of the disk a thin layer of I have found that the layer of record material need not be thicker, but may be thinner than l/100,of an inch; it is thus a mere film. i l

The record material which is particularly adapted for the production .of my improved sound record tablet consists of shellac as a binder and of an oxid ofv a' metal preferably the natural oxid of iron as the powdery body. To prepare this material for application to the tablet, I dissolve the'shellac in p alcohol and mix into this solution the requisite quantity of metal oxid, so that the whole mass forms a rather thin paint or emulsion. I have found the proportion of two parts of shellac to three parts of iron oxid, gives good results. This mode of preparing the record material by dissolving the sliellac or other resin, or gum, or other binder, and then mixing the oxid of iron or other proper substance into it, gives an" exceedingly intimate and uniform mixture, such as cannot be obtained by stirring the powdery body into the molten mass of the binder. Another important advantage results from this process of making the record material is that it avoids the necessity of fusing the shellac or other binder andthus the danger of deteriorating the same by the high temperature to which it must be subjected. The paint thus obtained is applied to thesized fibrous'disk either by a brush, as in ordinary painting, or the disk is immersed in the paint. The alcohol evaporates readily and there is then upon the disk a hard thin film of record material. pressed upon this disk, upon one or both surfaces, by heating the disk until the rec-v ord material becomes plastic, and then pressing onto it a suitably prepared matrix of a sound record, and holding it in contact with the disk until the latter has cooled and the record material has become quite hard.

`The record tablet constituted as above described is very much tougher andstronger l than record tablets entirely composed of record material, and it receives and retains the impress of a matrix fully as well as i-f it were entirely composed of record material, since the card board or other'fibrous base, particularly when' impregnated throughout with sizin yields-under the pressure of the matrix suciently for the purpose. At the same time my improved tablet is'very much cheaper than tablets which are made entirely of record material such as the sliellac mix-` ture now used.

While it is practicable to coat only one surface of the fibrous disk with the record material, I have found it referable to coat the disk on both sides an on the edges in order to prevent warping; and this I do Whether a sound record is impressed only' on one side or both.

While I have .found the record material composed of shellac and metallic oxid to be the best for the purpose of my invention,

I am by no means confined to the use of these materials. .Other compounds may be used although! not with like advantage.

I do not herein claim the improved tablet since it is claimed in my application Serial lNumber 204,024, filed April 20, 1904,' ofA whichthis application is a division.

Having now fully described 4my inveniio tion II claim :and desire to secure fby Letters Patent: p

1. The process of making :sound :record tablet blanks, which consists in impregnatin an absorbent base with a material that so tens under heat, and then producing upon such b ase a layer of 4gramophone .record material.

2. The process of making-sound record tablet blanks, which consists in impregnating a fibrous base with a material that softens under heat, and then producing upon such base a layer of gramophone record material.

3. The process of making sound record tablet blanks, which consists in impregnating a disk of fibrous material with thermoplastic material and then producing upon such disk a layer of gramophone record material.

4. The process of making sound record tablet blanks, which consists in producing a thermoplastic fibrous base and then covering the1 same with thermoplastic record materia l 'y 5. The process of making sound record tablet blanks, Which consists in impregnating a fibrous base with 'thermoplastic material, and then producing upon such base a layer ofv gramophone record material containing shellac.

6. The process of making sound record tablet blanks, which consists in producing a thermoplastic base of sut'ricient rigidity when cold to resist distorting forces, and then producing upon suchbase a layer of gramophone| record material containing shellac and a hardening material.

7. The process of making sound record tablets, which consists in roducing a thermoplastic base With suiiicient rigidity when cold to resist distorting forces, then producing upon such base a layer of ramophone record material containing shel ac and a hardening agent and then heating the tablet and impressing a sound 'record groove therein.

8. The process of makin sound record tablets, which, consists in pro ucing a fibrous -a fibrous basey with a material Which softens under heat, then covering such sized base with a film of gramophone record material, and then allowing the film to harden.

10. The rocess of making a gramophone record tab et blank which consists in firstfibrous base 'with -a material which softens under heat, then covering the sized `base with a film of fluid ramophone recordmaterial,

then allowing t e film to harden, then heating the lm and base until both the lm and sizmg are softened, and then impressing a soun record groove into the heated and thereby softened lm.

12. The process of making a gramophone record tablet which consists in rst sizing a brous base with a material Which softens under heat, then covering the sized base with a lm of gramophone record material, then allowin the film to harden, then heating the film an sized base to soften both the film and sizing, then impressing a sound record groove into the heated and thereby softened lm, and then cooling both the film and sizing while under pressure.

13. The method of making sound record tablets, which consists in producing a layer material, the latter being in disk form, and

impressing a sound record groove into the layer of ramo hone material while the said layer an the t ermoplastic material of the base are both softened by heat.

14. The method of making sound record tablets, which consists in producing a layer of gramophone material containing shellac upon a basic structure of thermoplastic material and fibrous material, the latter bein in disk form, and impressing a sound recor groove into the layer of gramophone material while the said layer and the thermoplastic material of the base are both softened by heat. 4

15. The method of making disk-shaped sound record tablets, which consists in pro- 1 ducing spaced layers of-gramophonemate rial separated by fibrous material in disk form and by thermoplastic material, and impressingl a .sound record groove into the gramop one material while the latter and the intermediate thermoplastic material are softened by heat. i

16. The method of making disk-shaped sound record tablets which consists in producing spaced layers of gramophone material separated by fibrous material in disk form and by thermoplastic material, and impressing a sound record groove into both layers of gramophone material While .the latter and the intermediate thermoplastic material are softened by heat.

17. The method of making disk-shaped sound record tablets which consists in pro- (lucing snaced layers of gramo hone material contaming shellac, separated y brous material in disk form` and by thermoplastic two subscribing witnesses. material7 and impressinv sound record l JOSEPH SANDERS. 5 grooves lnto both layers o gramophone ma- Witnesses:

terial While the latter and the intermediate F. T. CHAPMAN,` n thermoplastic material are softened by heat. EDWIN S. CLABKSON.

In testimony whereof I have signed my name to this specification in the presence of 

